Valiant plus al-82 and henry 2kw classic.

[w1cjf]

I have a friend that will be picking up a mint restored valiant within a couple days... He has some big ol boxes and wants to be able to run them with his valiant. I figured if he ran 2 of these Attenuator's he would be all set. I also will be doing this down the road when i decide to get a amp of my own. Question is how do we wire these up? Do we need to build a external box and do it that way? I know stock they are great radio's but with a couple of 3-500z graphites behind that audio it will make things even better.

Here is the ebay link for the attenuator's... any input would be greatly appreciated.

http://cgi.ebay.com/New-50-Watt-Hybrid-3-dB-50-ohm-Attenuator_W0QQitemZ390115385385QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item5ad4b06029

I know the boxes need about 20-25 watts input and figure the 2 might be enough, correct me if i am wrong maybe 3 of them?

[K5UJ]

What's wrong with just running the valiant right into the antenna?  Isn't it 3 x 6146 modulated by 2 x 6146?  Think that's around 180 w. carrier?  Not too bad if you got a strapper antenna (which I must admit seems to be getting harder to achieve these days with material and property costs and the antenna hater restrictions).

73

Rob
K5UJ

[N2DTS]

My guess would be about 120 watts of carrier out, with only two 6146's as modulators.
A 6146 is good for about 50 watts carrier, so three would max out at 150 watts.

A BIG amplifier will get that up to 300 watts carrier, after you put in about 1000 watts AC power to get the additional 150 watts out.

I have been amazed at all the good qso's I have been having on 80 meters lately using 25 watts of carrier
(not in prime time).
I have a low dipole with lobes east and west (half my signal goes out into the atlantic ocean).
Where are all those maritime mobil AM guys???

Brett

[w1vtp]

Well, the outfit (Henry Radio) is a reliable one.  I've had good dealings with them in the past.  RE: the attenuator -- it might be helpful if one is determined to go from 150 watts to 300+ watts but I think there might be a better way of accomplishing the job.

It seem to me that one might be better advised to go the route that Ken W2DTC did where he used a variac on the HV PS for his greatly revamped VK2 or his HB 6146 rig.  Of course, the fils and LV PS need to be separate from the variac.  With the screen(s) tied to the HV PS, he found that he could vary the power to exactly where he wanted it to be using a variac for his linears.  If you're talking about upping the AM carrier to 3 dB more, I'd be careful about tearing into a nice EFJ.  The 3 dB attenuator might do the trick but put it into a nice box and be careful about tuning up to a linear -- be careful when you first start out and keep the loading nice and light to avoid damage to the control grid of a $800 ceramic xmitting tube.

Al

[WQ9E]

On 160 through 40 a health Valiant will deliver about 140 watts carrier output.  Using the Henry to get around 300 watts carrier out is only a bit over a 3 decibel increase which isn't going to be significant under most conditions. 
Although the clipper circuit in the Valiant is generally disparaged, you will find that when the going is tough a bit of processed audio with the 140 watt carrier is going to get through better than the unclipped Valiant with the amplifier.

If you were running a Ranger, the amplifier would be worthwhile but with a Valiant it isn't worth the time or effort on AM.  My most used AM rigs are my Valiant, Viking 500, and Desk KW and pretty much any contact I can make with one I can also make with the other two.  The Desk KW does provide more impressive meter readings but run at the current AM legal limit the signal strength difference is roughly 1/2 S unit.  As a practical test, my first EU AM QSO on 75 was accomplished with my Viking 500/Pierson KP-81 (clipper engaged) since the Ranger and Desk KW wasn't clearly readable. 

If you don't like to use the built in clipper some external audio processing can be very useful at times.

Rodger WQ9E

[WBear2GCR]

Mmmm... I run a Valiant II with a pair of 6DQ5s in the modulator, and the rest of the speech amp redone... you can ask around, but I think I'm heard ok...

One idea  that might work is to A) reduce the B+ on the finals, and/or adjust the screen voltage and/or B) run only one 6146 in the final.

Both ideas are to reduce the output power - of course you'll want to install a 3 diode limiter or similar scheme to prevent "baselining" the rig. If you kept the stock modulator running at full bore, you'd then have really serious postive peak modulation available...

                          _-_-

PS. I don't think the 2K series will really do 300watt carrier + modulation... maybe, but I don't think it will, might be wrong on that...

[ke7trp]

I think this is a waste of time to try to run the atenuators like that.  One of my valiants is a strong one and it makes 165 watts of AM carrier. The Bird 43 in PEP mode is showing past 500 watts PEP! 

I will let you in a secret, You can simply pull final tubes out of the valiant. They are in P.  You need to be carefull when doing this. The tuning is going to change in this Class C Transmitter.

1. As you pull Final tubes you need to reduce loading down.  Three tubes 330ma, two tubes 220ma. One tube 110MA.

2. You need to lower Grid Drive. If you Dont, You will damage tubes for sure.  Use the Ranger (one 6146) as a tuning guide.

3. You need to really back the modulator (audio) down using the Modulator current meter. If you dont, You could pop that mod transformer in short order.

4. You need to neutralize the Rig again.

Some will tell you you should not do this. I knew a man that did this for 20 years with valiants and if you simply load the rig the correct way, you wont have trouble.  I ran one of my valiants this way for over a year into two 3-500s.  Never had any trouble. I also use this meathod to test 6146s. I just load up to 110MA, Read output power and note the Grid drive. Then start putting tubes in. I can test them in minutes and get a reading to find out if I have three matched tubes. all one at a time.

I ended up just putting it back to three tubes.  In the end, Two 3-500s is only going to give you 250 to 300 watts of AM carrier.  I just dont think its worth all the trouble. It wont be the difference in being heard or not.

[N3DRB The Derb]

not a good use of your transmitting resources. Run the valiant by itself and obtain a better matched exciter for the amp. you want to drop your power 6db so you can gain abt 3 db over the valiant? Thats not thinking right.

[W2VW]

A Valiant's audio isn't worthy of being amplified unless plenty of changes have been made to it.

Lowering screen voltage or backing off plate current will take you down the road to an even worse match than the mod iron already has.

Better off lowering the plate voltage and leave the modulator voltage where Junkston put it. This preserves the plate tank impedance and picks up dynamic headroom in the modulator which is sorely needed.

A low power modified Valiant into a Henry is worth doing.

[w1cjf]

A Valiant's audio isn't worthy of being amplified unless plenty of changes have been made to it.

Lowering screen voltage or backing off plate current will take you down the road to an even worse match than the mod iron already has.

Better off lowering the plate voltage and leave the modulator voltage where Junkston put it. This preserves the plate tank impedance and picks up dynamic headroom in the modulator which is sorely needed.

A low power modified Valiant into a Henry is worth doing.

So that would be the best way to get the valiant down in enough power to drive the al-82 or henry 2k by lowering the plate voltage? I am deffently not going to be poping out finals but just am looking for a alternative to drive these amps.

[W2VW]

An external supply using a variac would work. You need not worry about swinging choke inputs and all that other jazz. The supply is only powering a continuous load.


Power the final through the accessory plug. It would be nice to have a way to bring the Vally Ant up to near full power in order to load the following amplifier at max capability.

[WD5JKO]

Hi all,

  I once looked at the case where we might want to go from a 100 watt output plate modulated rig, and boost it up to legal AM limit, say around 375 watts. This entire thread seems devoted to the pros and cons of this issue with specific hardware in mind. Many good points made too.

  I have an idea that just might be possible if we open this idea up a bit to include other hardware options. Many years ago I contemplated this very issue, picked tubes, did many calculations, etc. I never built it though, and my notes are lost. But here is how it went, somewhat roughly since I cannot recall some of the exact details.

  Use an AMP, grounded grid, using low mu (u) tubes. This increases the drive power needed, and most of it feeds over to the plate side. To me this is better than using an attenuator. So I chose two 304 TL tubes, GG, Class B. The specs went something like this:

Input power: 100w (400w PEP)
Drive power: 25w
Feedthrough power: 75w
Plate input power: 900w
RF output power 300w (33% eff) + 75w = 375w (1500w PEP)

I'm not sure those numbers prove out in practice, but the idea I believe is doable.

Jim
WD5JKO

[WQ9E]

Before your friend puts all of this work into modifying a Valiant in order to drive an amplifier why not just acquire a Multi Elmac AF-67, AF-68, Ranger or similar rig which are already in the proper power range to drive the Henry?  Or better yet, most classic era 2KW pep amps are going to be much happier with the controlled carrier AM provided by rigs like the Heath DX-60 or Knight T-150.  

Otherwise the end result is going to be a chopped up Valiant running with an amp which will provide impressive peak meter readings but no practical performance increase in the real world where it counts.

The Henry amps are better than many of its competitors but using a continuous carrier AM rig driving it to its SSB PEP capability on modulation peaks is going to be running it (RF and power supply components) far hotter than original intent.  If your friend goes for "old buzzard" style transmissions then a suitable power limit would be its 1 KW input RTTY rating which is going to gain nothing in signal over the stock Valiant.  I have used Henry 2K and 3K series amps at contest stations in the past but in my opinion if you want to run legal limit AM without pushing the amp you should be looking at the 4K ultra series or above.  I remember the 3K version using a pair of 3-500Z's didn't stand up too well at the AF MARS station when it got heavy use at its rated RTTY input.

[ke7trp]

A few years back, I had this same question..  I decided to lower Screen volts.  I mounted a Small 6bq5 tube under the chassis.  I mounted a pot on the back.  This allowed me to vary the screen up and down. I can go from 50 watts AM to 150 AM with the turn of the pot.  I lost 15 watts with the Tube inline.  If I remove the tube, It goes back up to 165.

My SB 220 has the Grids grounded directly and a modified Power supply and filters. Any extra power is just feeding through. Amp ran warm. A desk fan providing some extra air in the direction of the amp fixed that. My SB 220 runs on a stiff 220 volt outlet also.

In the end, I went from 165 watts AM (stock valiant) to 300 Watts AM.  Worth it?  You decide. I did it for fun. I used to run this way. Normaly, I just use the Valiant with three good tubes at full power with the screen at full power.  I have other higher power rigs here now and dont run the SB220 on AM anymore. 

If you dont feel like pulling final tubes out, You can simply lower the screen down until you have 50 watts AM. Then, Switch it or make it variable.  I would MUCH rather do this then to have the valiant sitting there heating up resistors in the room.

Clark

[KM1H]

I have a low dipole with lobes east and west (half my signal goes out into the atlantic ocean).

Directivity is nil if its truly low.

On a different subject, I just realized last night that my HT-32B which Ive been using in the vintage SSB station transmits AM with both sidebands. I had a couple of 20M Q's this morning on AM driving the NCL-2000 to 350W carrier and reports were good. However I dont have a monitor on that bench so Ive no idea how bad good is

Carl
KM1H

[ke7trp]

I have a Friend that uses the HT32B on AM.  If you set it correctly with enough carrier, They sound great. If you set carrier to low on tuning they sound like hell.   

Clark

[w1cjf]

he was going to get a ranger but a local has a 110% restored valiant that he is going to be picking up. I know these transmitters are not meant for amps but he wants to run it with them so more power to him. The variac seems like the best way to do it. When i purchased my valiant the owner threw in a free monster variac and that is what i might use, it kinda makes sense insted of pulling tubes and all that jazz. He wants to have a historical piece of johnson history not some moded rig yet still him allow him to use one of his many many boxes he has.  Tuning would be the same using the variac on a lower power correct? Or would tune up need to be changed?  I dont currently have a amp so soon as mine comes online i will be runing just the radio without a amp so i am not worried. It is a big buy for him and he just wants to make sure that he will be able to use alot of his very expensive high end boxes with it. Thanks for the input guys.

73's
chris 

[ke7trp]

Your going to have to modify the rig to hook the variac up to the Plate supply.  Probably Drill holes in the back and run cables in or a socket. How can you possibly think that hooking up a variac is easier and less distructive then lowering screen volts or pulling tubes?

Clark

[W2VW]

You need not drill or permanently modify the Valiant. Build an external power supply using the variac. You can grab everything needed through the accessory plug except maybe the switched high B+ primary. I don't have the schematic in front of me now. I'd use a relay in parallel with the antenna relay to switch B+ on the external supply. All you need is an easy to find plate transformer.

The rig will load up similarly to original if the new B+ is the right number for the target output.

Add an external modulator later when you want to get into more trouble.

[kg8lb]

Your going to have to modify the rig to hook the variac up to the Plate supply.  Probably Drill holes in the back and run cables in or a socket. How can you possibly think that hooking up a variac is easier and less distructive then lowering screen volts or pulling tubes?

Clark

  With a little planning any mods made will be easily reversible .The accessory plug at the rear provides an in/out port and the internal wiring should be a snap.
  As far as a stock Valiant not being worth amplification ..Bullsott ! This is a hobby whatever you care to undertake is worthwhile. Ignore the stuffed shirt elitists and dive in.

[W2VW]

Your going to have to modify the rig to hook the variac up to the Plate supply.  Probably Drill holes in the back and run cables in or a socket. How can you possibly think that hooking up a variac is easier and less distructive then lowering screen volts or pulling tubes?

Clark

  With a little planning any mods made will be easily reversible .The accessory plug at the rear provides an in/out port and the internal wiring should be a snap.
  As far as a stock Valiant not being worth amplification ..Bullsott ! This is a hobby whatever you care to undertake is worthwhile. Ignore the stuffed shirt elitists and dive in.

Elitist my a$$. My statement has nothing to do with that. It's based on the shortcomings of the rig. The Valiant uses tetrode modulators without inverse feedback. The audio driver has plenty of issues. Distortion levels are fairly high. A legal limit signal with that kind of audio is not a good thing. If it were a Ranger things would be a little different.

[kg8lb]

Elitist my a$$.

  Yea , OK Scratch "elitist".  Still very worthwhile. If it is what you want to do, enjoy ! Even with stock audio. It has been done before with fine results.